javascript call function if exists code example

Example 1: check if function exists javascript

if (typeof payment === "function")
{
  // Do something
}

Example 2: javascript check if function exists

if (typeof sourceObj.someMethod === "function") { 
    // you are safe using the method
  	sourceObj.someMethod();
}

Example 3: js check if function exists

if (typeof yourFunctionName == 'function') { 
  yourFunctionName(); 
}